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R Sen

Publications and source records attributed to R Sen.

At least 91 records · Page 5Linked to original sources
PubMed1984

Ascaris lumbricoides and Ascaridia galli: biogenic amines in adults and developmental stages.

Ascaris lumbricoides var. hominis and Ascaridia galli contain 5-hydroxytryptamine, histamine, dopamine, and norepinephrine. The chick parasite showed lower levels of monoamines compared to human ascaris. Amine concentrations in females were higher than in males. In all specimens, 5-hydroxytryptamine was the highest while norepinephrine was found to be uniformly low. The female reproductive organ contained the maximum amount of dopamine while intestine was rich in histamine. A progressive increase in the concentrations of biogenic amines was noticed during development.

Animals↗
PubMed1983

Monoamine oxidase in adult Ascaridia galli.

Monoamine oxidase (MAO), catalysing oxidative deamination of biogenic monoamines, has been detected in adult Ascaridia galli. MAO was present in mitochondria and deaminated noradrenaline at the maximal rate, although serotonin, adrenaline, tyramine and dopamine were also degraded but more slowly. Of the organs studied, the body wall, female reproductive organ and intestine, the body wall (containing neuronal structures) showed highest MAO activity. Km value for chick ascarid mitochondrial MAO using tyramine as substrate was 1.66 X 10(-3) M and it was most active at 2.5 mM tyramine concentration, pH 7.5 and 40 degrees C. MAO of A. galli appeared to be thermolabile as nearly 80% of its activity was lost when the incubation temperature was increased 5 degrees above optimum.

Animals↗
PubMed1982

Molecular mobilities and the lowered osmolality of the chromaffin granule aqueous phase.

Carbon-13 spin-lattice relaxation times, T1, have been measured in whole adrenal medullary tissue slices, in suspensions of isolated chromaffin granules, in the reconcentrated chromaffin granule lysate, and in various model solutions containing catecholamines. ATP, chromogranins and Ca2+. Reorientational correlation times have been calculated at 10 degrees C using T1 data and nuclear Overhauser enhancements for protonated carbons on both catecholamines and nucleotides. Correlation times in all media are relatively short and characteristic of highly fluid aqueous phases. Adrenalin and ATP exhibit substantial differences in correlation times in all media, however, the ratio tau R (ATP): tau R(catecholamine) ranging from 2.4 in simple 3:1 adrenalin-ATP solutions to 4 in intact chromaffin granules. This difference, as well as the relatively high absolute reorientational mobilities of both components, confirms the importance of labile ionic interactions between ATP and catecholamines, but rules out the presence of high concentrations of base-stacked structures. Participation of the chromogranins in ternary complexes with catecholamines and ATP appears to be of minor importance. Ionic interactions to the protein are not reflected in either 13C T1 values or chemical shifts of arginine or glutamate sidechain resonances, or in the 13C chemical shifts of ATP or catecholamines. Very labile protein-ATP binding appears to be reflected in the correlation time measurements, however, which show selective immobilization of ATP relative to catecholamine in the presence of soluble protein. Osmotic measurements indicate that solutions containing adrenaline, ATP and Ca2+ are highly nonideal, but probably not sufficiently so to account fully for the osmotic stabilization of the chromaffin through their polyelectrolyte properties, exert a significant influence on the intragranular osmolality. The osmotic lowering due to polyion-counterion interactions has been estimated semiquantitatively using a theory developed by Oosawa.

Adenosine Triphosphate↗
PubMed1982

Water permeability of the chromaffin granule membrane.

NMR spin-lattice relaxation rates of solvent protons have been used to measure the water permeability coefficient of the chromaffin granule membrane. The technique involves labeling the chromaffin granule interior with Mn+2, which provides an efficient relaxation pathway for intravesicular solvent protons. Added Mn+2 spontaneously accumulates in the chromaffin granule matrix in the presence of the divalent cation-specific ionophore A23187 and is maintained against a large concentration gradient. In this way, the internal proton relaxation rate is readily augmented to values some 10(2)-10(3) times greater than that in the extravesicular water space. Transmembranal water transport permits solvent protons in the extravesicular water space, in which most of the observed NMR signal orginates, to sample the highly relaxive environment of the chromaffin granule matrix. By this process, water permeation shortens the observed relaxation rate. The diffusive water permeability coefficient of the chromaffin granule membrane has been measured over the temperature range 0-38 degrees C. The permeability coefficient measured at 25 degrees C is comparable to a previously reported value for planar lipid bilayers composed of ox brain lipids and cholesterol (Pd approximately equal to 0.37-0.53 10(-3)) cm X s-1 at 25 degrees C) but is substantially less than values for the plasma membranes of erythrocytes and Chlorella. Hypothesized hydrophilic "pores," thought to provide parallel permeation pathways in the latter membranes, appear to be absent in chromaffin granule membranes. The water permeation rate exhibits Arrhenius temperature behavior and does not reflect a phase transition at 32 degrees-34 degrees C observed previously in ESR spin-label studies of chromaffin granule ghosts.

Adrenal Medulla↗
PubMed1980

The soluble components of chromaffin granules. A carbon-13 NMR survey.

Carbon-13 NMR spectra of the reconcentrated chromaffin granule lysate have been obtained at 50 MHz and 62.9 MHz. The spectrum contains a number of assignable resonances in addition to those of the main soluble components (catecholamines, adenine nucleotides and chromogranin). Guanine and uridine nucleotides are present at levels of 0.13 and 0.08 mol/mol adenine nucleotides, respectively. Concentrations of cytidine nucleotides and NAD+ are below the detection limit (0.02 mol/mol adenine nucleotides). An unidentified low molecular weight species, thought to be an adenine-containing oligonucleotide, is also present. Ascorbic acid was observed at a concentration of 0.14 mol/mol adenine nucleotides, but both dopamine and dehydroascorbic acid were below the detection limit. Protein resonances agree well with the reported amino acid composition of chromogranin A, with the exception of tryptophan and glutamine which have not previously been measured. The concentrations of these residues are estimated to be 12 +/- 3 and 39 +/- 5 residues per 77 000 dalton unit of chromogranin A. Substantial intensity due to unsaturated fatty acid side-chains in solubilized lipid is seen in the olefinic carbon region and in the methylene region, suggesting the presence of lipoprotein. Unassigned carbohydrate resonances are also present, but are largely obscured by sucrose in the isolation medium.

Adenine Nucleotides↗
PubMed1979

Composition of the aqueous phase of chromaffin granules.

Nuclear magnetic resonance spectroscopy has been used to determine the composition of the aqueous phase of bovine chromaffin granules. Relative concentrations of catecholamines (epinephrine plus norepinephrine), ATP and chromogranins have been measured from integrated intensities in the proton spectra using computer simulation techniques. Most or all of the catecholamines (97 +/- 8%) are present in the aqueous phase and contribute to the high resolution spectrum. The catecholamine:ATP molar ratio (4.41 +/- 0.45) determined by NMR is close to the value (4.45) derived from biochemical assay indicating that most or all of the ATP is present with catecholamine in the aqueous phase. Catecholamine:protein ratios show that approximately 45% of the soluble protein freed by lysis is not NMR visible. Intensity from this fraction does not appear under highly denaturing conditions (8 M urea) but reappears after hydrolysis. This behavior is similar to that of recently isolated soluble lipoprotein complexes. Variations in the NMR spectra associated with (1) different preparative procedures; (2) different suspension media, and (3) increasing osmolality are described. The fact that high concentrations of epinephrine and ATP (approximately 700 mM total) are dissolved in the aqueous phase implies that solution phase interactions at least partially ionic in nature are responsible for the low internal osmolality of chromaffin granules in vivo. Ordered phases containing a substantial fraction of the total catecholamine in an osmotically inactive form are not present.

Adenosine Triphosphate↗
PubMed1976

Hemangiopericytoma of the hand. Case report.

We present one case of hemangiopericytoma of the hand. This lesion's clinical resemblance to glomus tumor is stressed; only the histological report could confirm the diagnosis.

Adult↗